Conversion of hard paraffin obtained by the catalytic hydrogenation of carbon monoxide



Sept. 16, 1958 H. KoLLlNG law-AL 2,852,546

CONVERSION oF HARD PARAFFIN OBTAINED BY THE cATALY'rIc HYDROGENATION oFcARBoN uoNoxIm-a Filed Feb. '7, 1955 2 Sheets-Sheet 1 2 Sheets-Sheet 2Sept. 16, 1958 H. KoLLlNG Erm.

, coNvERsIoN oF HARD PARAFFIN OBTAINED BY THE CATALYTIC HYDROGENATION 0FCARBON MONOXIDE Flled Feb 7 1955 HELMW /fm/f/e United Sttes .Y iai@Patented Sept. 16, 1958 CONVERSION OF HARD PARAFFIN OBTAINED BY THECATALYC HYDROGENATON OF CARBON MONOXIDE Application February 7, 1955,Serial No. 486,584

Claims priority, application Germany February 10, 1954 12 Claims. (Cl.260-450) This invention relates to improvements in the conversion ofhard parain obtained by the catalytic hydrogenation of carbon monoxideinto parains having melting points between 40 and 80 C.

By far the greatest part of the normally solid hydrocarbons formed bythe catalytic hydrogenation of carbon monoxide has more than 30 carbonatoms in the molecule corresponding to a boiling temperature of 460 C.at a pressure of 760 mm. Hg. These hydrocarbons from the catalytichydrogenation of carbon monoxide boiling above 460 C. are generallyreferred to as hard parafn. For the carbon monoxide hydrogenationeffected with iron catalysts, the average number of carbon atoms of thishard paraffin ranges between about 45 and 50.

Hard parain has a setting point of about 90-l00 C. as measured with arotating thermometer, and penetration numbers of about l. It nds use toa small extent for hardening slab para'in and increasing the pour pointthereof. The use of the major quantities of the hard parain is veryrestricted. The use of hard paraiiins in the production of polishingwaxes and shoe polishes presents difficulties, for example, due to theirrelatively poor oil-absorbability and insufficient retention power.Moreover, the pastes prepared with the addition of larger quantities ofhard paraffin have little temperature-resistance, i. e., the hardness ofthe pastes are insuflicient even at temperatures of as low as about 30C. For the electrical industries the hard parain is too brittle and hastoo high a contraction, although the electrical properties aresatisfactory. In spite of its high setting point, the hard paraffin ishardly suitable for paper impregnation, due to its extreme brittleness.lt can, therefore, not be used as a blending component for slab parainwith the same success as microcrystalline petroleum waxes.

For this reason, in the past hard paran was separated into fractions ofdifferent melting points by extraction with solvents. Parain fractionsobtained in this manner and having melting points of 70-80 C. arereferred to as Ozokerite and are used, for example, as blendingmaterials in the production of polishing waxes and shoe polishes, inelectrical engineering for fabricating precipitators, and for paperimpregnation.

The discontinuously operating solvent extraction of hard parain isextremely complicated and also very costly, due to the large circulatingquantities of solvent. A further disadvantage of this processing method'consists in that the extract fractions utilize only a relatively smallpart of the hard paraflin. The remaining extraction residue is even morebrittle than hard paraffin, and, therefore, still less suited for use ona large scale.

No commercially suitable processes have been known up to the presentwhich permit the separation of hard paraffin by distillation intofractions of different melting points and different properties. Theusual vacuum distillation only permits a fractionation up to atemperature, recalculated to normal pressure, of about 460 C. ABy thisprocess, hard parafn can only berecovered as a a second distillationzone.

residual fraction. Although statements are contained in the literatureon molecular distillations of hard parain carried out on a laboratoryscale and permitting the obtaining of hydrocarbons boiling above 460 C.as distillate fractions, processes of this kind are completely unsuitedfor a commercial processing of hard paraflin.

One object of this invention is a process for converting hard parainsinto paralins preferably melting between about 40 and 80 C. without theabove-mentioned diiculties and in an extremely simple manner. This, andstill further objects, will become apparent from the followingdescription:

ln accordance with the invention, the starting hard paraflins obtainedfrom the catalytic hydrogenation of carbon monoxide are passed through aheating zone and thermally treated in this Zone. The heating zone ispreferably deiined by a tubular system. The paraliins are passed throughthe zone so that they have a residence time of about 3 to 20 andpreferably 6 to l5 minutes in the zone. The heating in the zone iseffected to a temperature of about 390 to 450 and preferably 420 to 450C. while the pressure is maintained at atmospheric pressure or pressuresup to 20 kilograms per square centimeter.

After the treatment in the heating zone, gasoline and diesel oilhydrocarbons formed, boiling up to about 340 C., are distilled off in aiirst distillation zone, as, for example, in a distilling columnoperated under about atmospheric pressure. After the distilling off ofthis fraction boiling up to about 340 C., the distillation residue fromthe first distillation zone is distilled under reduced pressure of aboutl to 3 millimeters mercury absolute in The fraction of the materialboiling between about 340 to 550 C. is distilled olf in this seconddistillation zone, while the fraction boiling above about 550 C. isretained as distillation residue. The distillation in the seconddistillation zone is effected by depressurizing the hot distillationresidue from the first distillation zone to thereby utilize its heatcontent. The parafns having a melting point between about 40 and C. arerecovered from the distillate from the second distillation zone, whilethe distillation residue is preferably recycled to the process, as, forexample, by being mixed with fresh hard parains to be passed through theheating zone. In this manner, itl-60% of fresh hard wax may be mixedwith -40% of residues which remain in the vacuum distillation, i. e., inthe second distillation.

The equipment diagrammatically shown in Fig. l may be used for carryingout this process on a commercial scale.

The hard parain to be processed is admitted through line 1. The moltenhard paraffin is forced by pump 2 through the tubular coil 3 which islocated within the furnace 4 where it is heated to the temperaturesrequired in accordance with the invention. After a sufliciently longresidence time, the heated hydrocarbon mixture passes through line 5into the column 6 which is operated at about normal atmosphericpressure. The constituents to be distilled olf are led olf through line7 while the bottorn products are passed through line 8 and into a vacuumdistillation section which comprises the two columns 9 and 10. Theevaporated portions are led off fromthe top of the columns through lines11 and 12. The bottom product from column 9 passes through line 13 andinto column 10 where it is further heated under a sutlicient vacuum.

The bottom product of column 10 is led off through line 14 and, by meansof pump 1S, passed through line 16 and admixed to the entering hardparaffin at a point before the furnace 4.

The dimensions of the lines and distilling columns required are adaptedto the capacity intended of the unit,

n G it being possible to use commercially known installations as apattern.

The distillate obtained under vacuum in the second distillation zone maythen be separated in the known manner with the usual commercialequipment into the particular fractions desired, such as into fractionsof 340460 C. and above 460 C. with the fraction boiling above 460 C.remaining as the residue. The individual fractions can be freed fromoil-containing portions in the conventional manner by means ofextractiva de-oiling processes, or, if necessary or desired, by sweatingprocesses. It is possible in this manner to obtain oil-free paratiinshaving the particular melting points desired. It is of advantage if thefractions, prior to the de-oiling, are hydrogenated in the conventionalmanner, such as with nickel catalysts at temperatures of about 250 C. Bythis measure, an increased yield of oil-free parains is obtained.

A further separation by distillation of the distillate boiling betweenabout 340 and 550 C. may possibly be dispensed with. In this case, theover-all fraction, preferably after hydrogenation, is separated intoparafns having melting points of, for example, about 70 C., about 50-60"C., and about 40-45 C., and an oily fraction by subjecting it to astage-wise de-oiling at decreasing temperatures such as at temperaturesof between and 0 C. The principle of this working method may be seen,for example, from German Patent No. 850,044.

it is also possible, however, to separate the entire vacuum distillateby a solvent extraction at increasing temperatures effected in theconventional manner, such as with heptane or other low-boiling solvents.In this extraction, the low-melting portions are obtained at rst and thehigh-melting portions at last.

lt is also possible to subject the reaction product obtained in thefirst distillation Zone under normal pressure to an extraction withhydrocarbons or other solvents with the elimination of the vacuumdistillation and to recover the different parathns at increasingextraction temperatures. This working method, however, sacrifices asubstantial advantage of the process of the invention, i. e., theelimination of the complicated separation by extraction.

The process of the invention may also be carried out with particularadvantage in depressurizing the reaction i' product after the firstdistillation stage, in two or more series-connected vacuum columnsoperating with decreasing absolute pressure. In this manner, severaldistillates are directly obtained rather than a single distillate, and

the necessity of a subsequent separation by distillation "il iseliminated, a simple de-oiling of the different vacuum distillates beingsutiicient.

An increased yield of valuable parains having melting points of between60 and 80 C. is obtained by passing the hard parain iirst through atubular system heated to S70-410 C. with the residence periods beingexpediently between 6 and 15 minutes. The parain is then passed througha normal pressure distilling column and one or several vacuum distillingcolumns in the manner described above. The distillation residue boilingabove about 550 C. is then passed through a second tubular system whichis heated to temperatures of between 4l() and 450 C. and preferablybetween 420 and 430 C. with the residence times in this tubular systembeing expediently 6-15 minutes. The reaction product from the secondtubular system is then processed in the same subsequent distillingcolumns together with the reaction product obtained from the firsttubular system.

This embodiment of the process of the invention may be realized by meansof the arrangement of apparatus shown in Fig. 2.

The molten hard paraliin is admitted through line 17 and forced by meansof pump 18 through a tubular coil 19 which is located within the furnace20 where it is heated to the temperature required. After a. sufficientlylong residence time, the heated hydrocarbon mixture passes through line21 and into the column 22 operated under normal atmospheric pressure.The overhead products from this column are withdrawn through line 23while the bottom product passes through line 24 to the vacuumdistillation section comprising the two columns 25 and 26 which areconnected by line 27. The overhead products from the vacuum distillationsection are withdrawn through lines 28 and 29 while the bottom productof column 26, by means of line 30, pump 31, and line 32, is forcedthrough a tubular coil 33 which is also located in furnace 20. After thepassage through line 33, the heated bottom product is returned into theprocess cycle through line 21.

With this arrangement, a further embodiment of the process may becarried out with not only the hard paraffin, with with all of thehydrocarbons of the catalytic carbon monoxide hydrogenation boilingabove approximately 340 C. being charged. Also, in this case the feedproduct boiling above 340 C. is passed through the first tubular systemmaintained at somewhat lower temperatures, and the residue from the lastvacuum distillation is passed through the second tubular systemmaintained at higher temperatures. The processing of the reactionproducts is effected with the same subsequent distillation equipment.

, It is also possible, of course, to adjust the initial boiling point ofthe residue from the last vacuum distillation to temperatures lower thanabout 550 C. such as 480 or 500 C. Thus, for example, all of thehydrocarbons boiling in excess of 500 C. are returned to the heatersystem. In this case, the reaction product contains less parafns havingmelting points of 60-80o C. and more paratins having melting points ofbetween and 60 C.

The process of the invention is commercially operated without anydiiculty. A formation of undesirable residual products or of carboncausing obstructions of the apparatus does not occur. It is possiblewith the process of the invention to convert all of the hard parafn intovaluable paraftins` having melting points of about 40-80 C. with theyield being about 7080%, and with 80-90% of these paratins beingparticularly valuable, due to their melting point ranging between about70 and 75 C.

It is already known to thermally crack products from the carbon monoxidehydrogenation boiling above 450 C. to produce therefrom fractionsboiling between 320 and 450 C., which have been converted into fattyacids by oxidation. In this cracking process, however, quiteconsiderable quantities of gases and low-boiling hydrocarbons areobtained, so that the yield of paralins having melting points of about60 C. is very low and parains having melting points' in excess of 60 C.cannot be obtained at all.

It has also been suggested to treat hard paraiiins from the carbonmonoxide hydrogenation at 400-450 C. until the hard paran has turnedinto salve-like products similar to jelly. In this method, the treatmentis effected for 2-18 hours. In contrast to this process, the process ofthe invention yields no jelly-like products at all, but solid, oil-freeparaflins.

The process of the invention makes possible the conversion of hardparain from the catalytic carbon monoxide hydrogenation into high yieldsof parans melting between about 40 and 80 C., and preferably into paranshaving melting points of 80 C., which may widely be used in theproduction of polishing waxes and shoe polishes, in electricalengineering and in paper impregnation. Moreover, the parati-ins producedin accordance with the invention and having melting points of about C.are suitable for the manufacture of candles. Particularly heat-resistantcandles for the tropics with excellent combustion properties can beproduced from, for example, 1 part of paran having a melting point ofabout 68-75 C., and, for example, 1 part of paratiin having a meltingpoint of about 56-62" C.

The process of the invention processes the hard parafns from thecatalytic hydrogenation of carbon monoxide, which previously had littleuse, into valuable, almost unlimitedly saleable products. This is ofparticular importance, since by far the greatest part of the normallysolid parain hydrocarbons from the catalytic carbon monoxidehydrogenation consists of hard paraffin, and the hitherto non-existingsales opportunities for this hard paraffin may be very disadvantageousfor the Fischer-Tropsch synthesis from the economical point of view.

Example 1 A mixture consisting of parts by weight of a hard paratnboiling above 460 C., obtained by carbon monoxide hydrogenaton with ironcatalysts and having a molecular weight of 630, and 65 parts by weightof a distillation residue boiling above 550 C. and derived from theprocess cycle was passed at normal pressure through a tube heated at 425C. with the residence time within the tube being 8 minutes. After thepassage through this tube, -the gaseous reaction products formed in thetube and the liquid portions boiling up to about 340 C. were removedfrom the reaction 'product in a rst distilling column. The residue wasdepressurized in a second distilling column operating under an absolutepressure of 1 mm. Hg and from which while utilizing the heat content ofthe reaction products, the reaction products boiling between 340 and 550C. were drawn oi overhead While the residue boiling above 550 C. wasmixed with fresh hard parain and returned into the tube heated to 425 C.

In the vacuum column, the head temperature was 275 C. and the bottomtemperature 375 C.

Based on the hard paraffin charged, the following reaction products wereobtained:

Overhead products in the rst distillation:

84.7 wt.percent of a fraction boiling between 340 and The fractionboiling between 340 and 550 C. was

separated in a conventional commercial vacuum distillation unit at anabsolute pressure of 3 mm. Hg into a distillate boiling between 340 and460 C. and a residue boiling between 460 and 550 C. Based on the hardparaffin charged, the yield was as follows:

19.2 wt.percent of a fraction boiling between 340 and 65.5 wt.percent ofa fraction boiling between 460 and These two fractions, after theaddition of 5% by weight of a hydrogenation catalyst (100 Ni, 15 MgO, 50kieselguhr), were now separately stirred for 1 hour at 250 C. and ahydrogen partial pressure of 50 atmospheres in an autoclave with stirrerand subsequently separated from the catalyst by ltration. Thehydrogenated fractions were processed as follows:

One part by weight of the fraction boiling between 340 and 460 C. wasstirred up at 60 C. with three parts by weight of a solvent consistingof 35% of benzene and of isopropanol, cooled to 20 C. and filtered atthis temperature. The ltration residue was washed with small amounts ofthe same solvent mixture. After evaporation of the solvent, an oil-freeslab parain, having a pour point of 57.5 C., was obtained.

The filtrate obtained was further cooled te 5 Q,

and again ltered at this temperature. `The filtration residue was washedand then freed from the solvent. This resulted in an oil-free softparain having a pour point of 44 C. The solvent mixture was separatedfrom the filtrate by distillation. The residue consisted of anextraction oil having a pour point of 25 C.

The yield, based on the hard parafn charged, was as follows:

9.7 percent by weight of slab paran 3.9 percent by weight of soft parain5.6 percent by weight of extraction oil 59.0 percent by weight of parainhaving a pour point of 73.5 C. 6.5 percent by weight of extraction oil.

The total yield obtained from parts of hard paraiiin was as follows:

fraction boiling between Example 2 A mixture consisting of 30 parts ofthe hard paraffin used in Example l and boiling above 460 C. and 70parts of a distillation residue boiling above 550 C. Was passed atnormal pressure through a tube heated to 430 C. with the residence timebeing 6 minutes. After the passage through this tube the gas and theliquid portions boiling up to about 340 C. were separated in a firstdistilling column operating at normal pressure. The residue wasdepressurized in a second distilling column operating at an absolutepressure of 1 mm. Hg and from which, while utilizing the heat content ofthe reaction product, the reaction products boiling between 340 and 550C. were withdrawn as distillate, while the residue boiling above 550 C.was returned into the heater tube.

Based on the hard paraffin charged, the following overhead products wereobtained:

In the first distillation:

0.8 wt.percent of gas 3.8 wt.percent `of a fraction boiling between 30and 11.0 wt.percent of a fraction boiling between 160 and In the seconddistillation:

84.4 wt.percent of a fraction boiling between 340 and The fraction340-550 C. was subsequently hydrogenated in the same manner as inExample 1 and then processed as follows:

One part by weight of the fraction S40-550 C. was stirred up at SO C,with 5 parts by weight of a solvent mixture consisting of of benzene and50% of isopropanol, cooled to 20 C., and filtered at Vthis temperature.The filtration residue was washed with small amounts of the solventmixture. After evaporation of the solvent, an oil-free paraffin having apour point of 70 C. was obtained. The resulting ltrate was subjected todistillation in which a distillate consisting of about 66% of benzeneand 33% of isopropanol distilled off as an azeotropic mixture. Thisdistillation was continued until about of the solvent mixture wasdistilled off. The distillation residue was cooled to 20 C. and filteredat this temperature. The filtration residue was washed with smallamounts of solvent mixture and then freed from the solvent. Thisresulted in an oilfree slab paraffin having a pour point of 52 C. Thefiltrate was then cooled to 5 C. and filtered at this temperature. Thefiltration residue was Washed and subsequently freed from the solvent.This resulted in an oil-free soft parafiin having a pour point of 43 C.The solvent was separated from the filtrate by distillation. The residueconsisted of an extraction oil having a pour point of 26 C.

The total yield obtained in this manner from 100 parts of hard parainwas as follows:

parafiin having a pour point of 0.8 Wt.percent of gas Example 3 35 partsby weight of the hard paraiin mentioned in Example l were passed atnormal pressure through a tube heated to 430 C. with the residence timebeing 6 minutes. Through a second tube, which was also heated to 430 C.,there were passed parts by Weight of a distillate boiling above 550 C.with the residence time being 8 minutes. Both of the reaction productswere combined, and then the gaseous and liquid reaction products boilingup to about 340 C. were separated in a first distilling column operatingat normal pressure. The residue was `.depressurized in a second columnoperating at an absolute pressure of mm. Hg. At a head temperature of300 C. and a bottom temperature of 400 C. the portions boiling between340 and 460 C. were separated as distillate. The residue from the seconddistilling column was then depressurized in a third distilling columnoperating at an absolute pressure of 1 mm. Hg. At a bottom temperatureof 375 C. and a head temperature of 290 C. the portions boiling between460 and 550 C. were separated as distillate, while the residue boilingabove 550 C. was returned into the second tube heated to 430 C.

Based on the hard paraiiin charged, the following overhead products,were obtained:

in the first distillation:

0.5 W'tfpercent of gas 2.2 wt.percent of a fraction boiling between 30and 160 `C. 5.1 wt.percent of a fraction boiling between 160 and 340 C.

'In the second distillation:

12.2 wt.percent of a fraction boiling between 340 and In the thirddistillation:

80.0 wt.percent of a fraction boiling between 460 and The two fractions340-460 C. and i60-550 C. were separately hydrogenated and de-oiled, asdescribed in Example l.

The total yield obtained from parts by weight of hard parafiin was asfollows:

71.8 Nt-percent of parain having a pour point of 5.7 wt.percent of slabparafiin having a pour point of 2.5 wt.percent of soft paraliin having apour point of 22.2 wt.-percent of extraction oil having a pour point of5.l vut-percent of a fraction boiling between -340 C.

0.5 wt.percent of gas.

We claim:

l. Process for the treatment of hard parafiins obtained by the catalytichydrogenation of carbon monoxide, which comprises passing the hardparafiin through a heating zone with a residence time therein of about 3to 20 minutes, while heating the paraflin in said zone 1o a temperatureof about 390 to 450 C. at about normal pressure, thereafter distillingofi the fraction boiling up to about 340 C. at about normal lpressure ina first distillation zone, distilling off from the residue of the firstdistillation zone the fraction boiling between about 340 and 550 C. in asecond distillation zone, at a reduced pressure of about 1 to 3 mm. Hgabsolute while utilizing the heat content of said residue, admixing thesecond distillation Zone residue boiling above about 500 C. with freshhard paran, recycling said mixture to said first heating zone andrecovering parafns having a melting point between 40 and 80 C. from saidlast mentioned fraction.

2. Process according to claim l, in which said heating Zone is `asubstantially tubular-shaped zone.

3. Process according to claim 2, in which said heat ing in said heatingzone is effected at a temperature of about 420 to 450 C.

pressure, thereafter distilling 4. Process according to claim 3, inwhich said hard parain is passed through said heating Zone with aresidence time therein of about 6 to 15 minutes.

5. Process according to claim l, in which said distillation in saidsecond zone is effected in at least two distillation stages withdecreasing pressure in each subsequent stage and in which said parafiinis separately recovered from the distillation fraction from each stage.

6. Process according to claim 1, in which said distillation in saidsecond distillation zone is effected, so that the distillation residuehas an initial boiling point of not less than about 480 C.

7. Process according to claim l, in which said fraction from said seconddistillation zone boiling between about 340 and 550 C. is hydrogenatedprior to said recovery.

8. Process according to claim 7, in which said recovery is effected withdistillation.

9. Process according to claim 7, in which said recovery is effected withselective solvent extraction.

10. Process according to claim 7, in which said recovery includesremoving the oil from said fraction.

11. Process for the treatment of hard parafiins obtained by thecatalytic hydrogenation of carbo-n monoxide, which comprises passing thehard parafiin through a heating zone with a residence time therein ofabout 3 to 20 minutes, while heating the parafiin in said zone to atemperature of about 370 to 410 C. at about normal oi the fractionboiling up to about 340 C. at about normal pressure in a firstdistillation zone, distilling off from the residue of the firstdistillation zone the fraction boiling between about 340 to 550 C. in asecond distillation zone, at a reduced pressure of about 1 to 3 mm. Hgabsolute while utilizing the heat content of said residue, thereafterpassing the distillation residue from said second distillation zone to asecond separate heating zone and heating the same therein to atemperature between about 410 and 450 C., thereafter admixing the seconddistillation zone residue with the residue from said first mentionedheating zone, recycling said mixture to said rst distillation zone andrecovering parains having a melting point between 40 and 80 C. from saidlast mentioned fraction.

12. Process according to claim 11, in which the distillation residuefrom said second distillation zone is passed through said separateheating zone with the residence time of about 6 to 15 minutes and heatedtherein to a temperature of about 420 to 430 C.

References Cited in the file of this patent UNITED STATES PATENTSFellows Dec. 28, 1937 Goethel et al Sept. 12, 1939 Catterall Apr. 8,1952 Garner et al June 16, 1953 Loughran Sept. 8, 1953 FOREIGN PATENTSAustralia Ian. 30, 1951 Germany Sept. 22, 1952 OTHER REFERENCESSachanen: Conversion of Petroleum, Reinhold Publishing Corp., New York,1940, p. 377.

1. PROCESS FOR THE TREATMENT OF HARD PARAFFINS OBTAINED BY THE CATALYSTHYDROGENATION OF CARBON MONOXIDE, WHICH COMPRISES PASSING THE HARDPARAFFIN THROUGH A HEATING ZONE WITH A RESIDENCE TIME THEREIN OF ABOUT 3TO 20 MINUTES, WHILE HEATING THE PARAFFIN IN SAID ZONE TO A TEMPERATUREOF ABOUT 390 TO 450*C. AT ABOUT NORMA PRESSURE, THEREAFTER DISTILLINGOFF THE FRACTION BOILING UP TO ABOUT 340*C. AT ABOUT NORMAL PRESSURE INA FIRST DISTILLATION ZONE, DISTILLING OFF FROM THE RESIDUE OF THE FIRSTDISTILLATION ZONE THE FRACTION BOILING BETWEEN ABOUT 340 AND 550*C. IN ASECOND DISTILLATION ZONE, AT A REDUCED PRESSURE OF ABOUT 1 TO 3 MM. HGABSOLUTE WHILE UTILIZING THE HEAT CONTENT OF SAID RESIDUE, ADMIXING THESECOND DISTILLATION ZONE RESIDUE BOILING ABOVE ABOUT 500*C. WITH FRESHHARD PARAFFIN, RECYCLING SAID MIXTURE TO SAID FIRST HEATING ZONE ANDRECOVERING PARAFFINS HAVING A MELTING POINT BETWEEN 40 AND 80*C. FROMSAID LAST MENTIONED FRACTION.